1. Field of the invention
The present invention provides a composite electrode material and a method for manufacturing the same, a composite electrode comprising the said composite electrode material and a method for manufacturing the same, and a lithium-based battery comprising the composite electrode.
2. Description of Related Art
Lithium ion battery (LIB) is a widely known lithium-based battery due to its high energy storage ability. It is widely used, for example, in electric vehicles as well as in electronic and medical devices. The anode material of the common lithium ion battery is graphite. Through reversible insertion and extraction of lithium in active materials such as graphite, electrical charges are stored. Since mesocarbon microbeads (MCMB) have a theoretical capacity of 372 mAh/g (based on LiC6) and have a low potential (0-0.3 V vs. Li/Li+) mesocarbon microbeads are one of the common anode materials. However, the capacity of mesocarbon microbeads could not satisfy the future high energy demand.
As a result, materials which form alloys with lithium and can incorporate larger amount of lithium per unit weight, such as Sn, Sb, Si, and Ge, have thus been attractive for the replacement of graphite-based anode. Among these materials, silicon has a much higher theoretical capacity near 4200 mAh/g (ca. Li4.4Si), which is around ten times of that for the common anode material, mesocarbon microbeads. However, as lithium ion is inserted into silicon-based anode, volume expansion of silicon-based anode of approximately 380% will occur. Repetitive expansion and contraction of silicon-based anode will cause silicon to break apart and eventually pulverize. This not only results in additional consumption of electrolyte in forming solid-electrolyte-interphase, but also leads to the loss of electrical contact between silicon particles and the current collector of a battery cell, causing rapid capacity fading during cycling. In addition, silicon has much lower electrical conductivity than the standard graphite-based anode material. Hence, suppressing the breaking of hulk silicon and maintaining good conductivity inside the battery structure are the goals for many research efforts.
Therefore, there is a need to develop a composite electrode material, which can still demonstrate good charging and discharging characteristics during multiple cycling, in order to improve the efficiency of conventional batteries that use graphite-based electrodes.